The addition of perfumes to consumer products is well established, particularly for products such as household cleansers, laundry products and personal cleaning and cosmetic products. Normally, the perfume is simply admixed with the other components of the product to produce a homogeneous product but in some cases this process may be facilitated by the use of a solubiliser, such as a emulsifier or co-solvent, to disperse the perfume more readily into the product. Whilst in general the perfume does not contribute to the functional performance of the product it does serve to improve its aesthetic appeal by imparting a pleasing odour to the product both on storage and in use. Additionally it may impart a pleasing odour to substrates on which the product is used, such as skin and hair.
Where a perfume is added to a product the nature of the product can affect its performance in a number of ways. For example, the components of the product may chemically interact with the perfume; the performance of the perfume may be hindered by interactions with component(s) of the product and this may affect both its perception in the package and in use; the longevity of the perfume may be affected. Various methods are known in the art to address these problems. One approach to optimising perfume performance in products is to empirically tailor the perfume by selecting those ingredients which are known in the art to perform well in particular products. In some cases, this can severely constrain creativity in designing a suitable perfume and may have increased cost implications for the successful perfuming of a product. In another approach, encapsulation technology can be used to stop or hinder adverse interactions between perfume and product components or to allow tailored release i.e. to control the release profile. Well-known examples of such encapsulation or controlled delivery technology include processes and products described in EP 303 461 (Unilever), U.S. Pat. No. 3,516,941 (Minnesota Mining & Manufacturing Corp.), EP 332 175 (Lion Corp.), U.S. Pat. No. 4,842,761 (IFF Inc.), EP 334 666 (Union Camp Corp.), GB 2,141,730 (Colgate-Palmolive Co.), EP 332 259 and EP 332 260 (both Procter and Gamble Inc.). Often these methods result in an appreciable on-cost for the perfuming of products.
It is known that liquid crystalline phases can help to stabilise skin cream emulsions (G. Dahms in "Cosmetics and Toiletries" Vol. 101 no. 11 (1986), pp. 113-115) and they are claimed to offer advantages in moisture retention on the skin. In a similar way liquid crystalline phases can be used to form vesicles and in recent years there has been extensive literature describing the preparation and application of such vesicles known as "liposomes". Bioemulsifiers, such as phospholipids (e.g. lecithin), have been the principal materials used in the preparation of such liposomes and are being increasingly exploited in a variety of personal products, which are claimed to offer exceptional benefits as skin moisturizers, e.g. as described in EP 120 722 (Parfums Christian Dior), U.S. Pat. No. 4,508,703 (Parfums Christian Dior), U.S. Pat. No. 3,957,971 (Lever Bros. Co.). Additionally, some non-ionic emulsifiers have also been used to form liposomes with similar benefits being claimed, see U.S. Pat. No. 4,217,344 (L'Oreal), U.S. Pat. No. 4,670,185 (Lion Corp.). In WO 88/06883 (Micro Vesicular Systems) paucilamellar vesicles are suggested for a number of applications in the medical and therapeutic field. A method of preparing multilamellar lipid vesicles using certain non-ionic emulsifiers and a sterol is disclosed in WO 88/06882 (Micro Vesicular Systems). A similar method wherein hydrophilic and amphiphilic components are encapsulated in such vesicles is disclosed in WO 88/06881 (Micro-pak Inc.). In EP 347 306 compositions with high perfume concentration are described which appear to contain separate bubbles of non-ionic emulsifier (based on polyglycerol derivatives) and droplets of perfume, surrounded by a continuous aqueous phase. GB 1,439,244 describes liquid crystalline compositions prepared by mixing an aqueous phase containing an amphotheric surfactant with an organic liquid. This liquid, which may contain perfumery materials, must itself be capable of forming the required liquid crystalline structure in combination with the aqueous phase. However, the organic liquid does not appear to be surrounded, and thus protected, by the liquid crystal structures. The compositions are described as giving enhanced substantivity of the organic liquid to skin, hair etc, when directly applied thereto. Preferably, the aqueous phase of the compositions is acidified to a pH near the isoelectric point of the amphoteric surfactant to obtain maximum substantivity. Finally, the liquid crystalline compositions described lose their substantivity in combination with most anionic surfactants.
On the other hand, EP 217 105 describes, lamellar-type single phase liquid crystal compositions for application to the skin, comprising hydrophilic nonionic surfactants having an HLB of 10 or more, water soluble substances, an oily substance and a relatively small amount (preferably below 30%) of water. These compositions are cited to have the advantage of being easily washed of the skin with water, i.e. being the reverse of substantive.
Finally, EP 316 728 and EP 368 146 describe clear microemulsion cleaning compositions comprising anionic and nonionic surfactants, co-surfactants, perfume and water. These products are intended for removing oily and greasy soils.
However, none of these references suggests to use vesicles or liposomes or or similar structures to incorporate a perfume in a personal product so as to protect it against interaction with other components present in the product and enhance its performance.